Tuesday, 08 August 2017 09:20

Grafted grapevine standard – high health vines

Written by  Edwin Massey
 Bundled certified vines. Bundled certified vines.

The first question that needs to be answered is; What should a high health vine look like?

The Grafted Grapevine Standard (GGS) provides assurance to growers, viticulturists, winemakers, and other stakeholders, that grafted grape vines which are certified according to this standard, can be certified as “high health plants”. On its establishment the GGS focused primarily on minimising the probability of material infected with Grapevine Leafroll associated virus (GLRaV -3). Over time, the GGS has expanded in scope has to cover other components of vine health. This column explores in more detail what “high health” vines certified under the GGS should look like and highlights the importance of excellent viticultural practice and a suitable environment to ensure a quality crop and exceptional wine.

Physical specifications - Check your vines on delivery

New Zealand Winegrowers encourages all our members to only use vines that are certified under the GGS. Nonetheless, just because you have purchased certified vines does not guarantee that 100% of these vines will grow as expected or produce a bumper crop in a timely manner.

From time to time isolated issues regarding vine quality do occur. The best time to check on whether there are any issues with your vines is prior to planting. At this time, other factors such as the quality of the viticulture or environmental factors can be removed from consideration. It makes sense to check an appropriate sample of the total number of vines you have purchased. This isn’t a fixed percentage instead the total number checked should get larger depending on the size of your order.

Primarily, this check will help to ensure the vines are consistent with section 4 of the GGS regarding their physical specification. In summary these specifications put in place quality standards on:

- The length, breadth and curvature of the vine

- The quality of the graft union

- The quality of the root stock

Be prepared to get your hands dirty; investigate the quality and size of the root mass; measure the breadth of the stem; examine the graft union for damage and give it a pressure test. Be aware that the GGS permits deviation from required physical specifications of up to 2% of samples from all grafted plants in a specific lot or batch. This margin is put in place to recognize that grafted grape vines, as living products will show a natural variety around a mean value.

Viticulture and the environment – they’re really important!

Even the best high health vines won’t grow without due care in planting and skillful and appropriate viticulture. Moreover, even the best vines with the best viticulture won’t lead to the best outcome if the vineyard environment is not conducive to growing high quality grapes. If you need advice on how to take the best care of your vines post planting don’t be afraid to ask for help. Many nurseries provide growers with guidance on aftercare post planting and there are several reputable viticultural consultants who can provide advice as needed.

What should I do if I have concerns?

If, following your sample, you don’t think your vines are up to standard contact the nursery you purchased them from and let them know your concerns. It’s important to have the conversation with your nursery, to form an ongoing business relationship with them and seek resolution if required. If you have serious concerns about the ongoing quality of vines being sold as GGS certified vines please contact me at New Zealand winegrowers.

Feedback opportunities

New Zealand Winegrowers works with a Technical Review Group (TRG) of nurseries, wine industry members, independent consultants and research scientists to ensure the GGS provides sufficient assurance to growers, viticulturists, winemakers and other stakeholders and consumers that certified vines are high health. At the most recent TRG meeting in February the group decided that the GGS should be strengthened by including an opportunity for purchasers to provide feedback on the physical specification requirements should they think they are not up to what’s set out in section 4. New Zealand Winegrowers is working to develop and publicize this feedback mechanism as soon as possible.

It’s the Vine – not the nursery

The GGS certified the grapevine itself rather than the nursery you purchase that grapevine from. That means nurseries can still sell a range of vines. Second grade vines have been produced using the same procedures and standards as GGS certified vines throughout the growing season, however have generally failed to meet the physical specifications required by the GGS. New Zealand Winegrowers encourages members to reduce the risk and make sure you specify that you want certified high health vines. If in doubt – look for the logo, as shown below.

If you need more information on the GGS download the factsheet summary here.

Conclusion and next steps

New Zealand Winegrowers will work to promote grower education on section 4 of the GGS and will include a session on “what to look for” at the upcoming Bragato conference later in the year. All nurseries that are members of the Vine Industry Nursery Association (VINA) would welcome questions about the benefits of buying vines certified to the GGS.

If you have any questions about the GGS or biosecurity please contact me on:

This email address is being protected from spambots. You need JavaScript enabled to view it. or 021 1924 924.

 

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